JPH01171886A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To ensure excellent releasability of an ink layer, obtain a favorable printed image and enable safe and easy production, by providing an anchor layer containing a watersoluble polymer between a base and a heat-fusible coloring material layer. CONSTITUTION:A water-soluble polymer to be used may be, for example, polyvinyl alcohol, polyvinyl pyrrolidone, gelatin, carboxylmethyl cellulose, methyl cellulose, polyethylene oxide, gum arabic, a water-soluble polyester, water-soluble polyurethane, a water-soluble acrylic polymer or a watersoluble polyamide. The water-soluble polymer preferably has a softening point of at least 100 deg.C, the content thereof is ordinarily at least 5wt.%, and preferably contains a filler. The average particle diameter of the filler is ordinarily 0.2-3mum, and the film thickness of an anchor layer is ordinarily 0.05-3mum.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a thermal transfer recording medium, and more specifically, the present invention relates to a thermal transfer recording medium, and more specifically, the ink layer has good releasability to achieve excellent printing quality and can be used safely and easily. The present invention relates to a thermal transfer recording medium that has a structure that can be manufactured and that can be suitably used as a thermal recording medium for, for example, facsimile machines and printers.

[Prior Art and Problems Therewith] The thermal transfer recording method usually uses a thermal transfer recording medium having a heat-fusible ink layer formed by dispersing a colorant in a heat-fusible substance on a sheet-like support.

The ink layer is layered on a transfer medium (generally paper) and heated by a thermal head from the support side of the thermal transfer recording medium, and the molten ink layer is transferred to the transfer medium to create ink according to the heated area. It forms an image.

Therefore, in order to obtain a good printed image using the thermal transfer recording method, the ink layer on the thermal transfer recording medium must be accurately transferred to the transfer medium according to the heated portion by the thermal head.

That is, in a thermal transfer recording medium, the ink layer needs to be accurately peeled off from the support depending on the heated portion.

In order to meet this requirement, a technique has long been known in which a layer called a release layer is interposed between the support and the ink layer for the purpose of improving the releasability of the support.

In general, a release layer is a layer that is mainly composed of a heat-melting substance such as wax, and further contains a thermoplastic resin, and is usually coated by heating until each component melts, or by applying an organic solvent. It is formed on a support by a method of coating a coating solution in which the oxide is dissolved or dispersed in .

In general, in order to obtain a printed image with good quality, it is desirable that the ink layer be transferred from the support side to the transfer medium by interfacial peeling between the release layer and the adjacent ink layer. .

However, in conventional release layers, in addition to the above-mentioned interfacial peeling, interfacial peeling occurs at the interface between the release layer adjacent to the support and the support, and cohesive failure peeling occurs within the release layer. There is a problem, and when such peeling occurs, it is difficult to say that the quality of the printed image obtained is sufficiently good.

In addition, especially when coating a release layer on a support using an organic solvent, it may worsen the working environment, require special equipment for fire prevention, and increase production costs. There is also the problem that sometimes.

This invention has been made based on the above circumstances.

That is, an object of the present invention is to provide a thermal transfer recording medium that has an excellent releasability of an ink layer, can obtain a good printed image, and can be manufactured safely and easily.

[Means for solving the above-mentioned problems] In order to solve the above-mentioned problems, as a result of extensive studies, the present inventor has developed a method that uses a water-soluble polymer between the support and the heat-melting coloring material layer. The heat-sensitive transfer recording medium provided with the anchor layer contains excellent releasability of the heat-fusible coloring material layer and can achieve good print quality, and the anchor layer can be applied in water, making it safe and easy. This invention was achieved by discovering that it can be manufactured.

That is, the structure of the present invention is a heat-sensitive transfer recording medium characterized in that an anchor layer containing a water-soluble polymer is provided between a support and a heat-melting coloring material layer. ' The thermal transfer recording medium/body of the present invention is formed by laminating at least an anchor layer 2 and a heat-melting coloring material layer 3 in this order on a support l, as shown in FIG. It is.

1.Support 1. The support in the thermal transfer recording medium of the present invention preferably has good heat resistance strength and high dimensional stability.

The materials include, for example, papers such as plain paper, capacitor paper, laminated paper, and coated paper; resin films such as polyethylene, polyethylene terephthalate, polystyrene, polypropylene, and polyimide; composites of paper and resin films, and aluminum foil. All metal sheets such as the above are preferably used.

The thickness of the support is usually 3QILm or less, preferably 2QILm or less.
~6 gm. If the thickness of the support exceeds 30 pm, thermal conductivity may deteriorate, leading to deterioration in printing quality.

In the thermal transfer recording medium of the present invention, the structure on the back side of the support may be arbitrary, and for example, a backing layer such as an anti-sticking layer may be provided.

-Anchor Layer- One of the important points in this invention is that an anchor layer containing a water-soluble polymer is provided between the support and the heat-melting coloring material layer described in detail below.

The anchor layer in this invention promotes interfacial peeling between the anchor layer and the hot-melt coloring material layer when the hot-melting coloring material layer is peeled from the support, and improves the peelability of the hot-melting coloring material layer. It has the effect of improving the quality of printed images.

Moreover, the water-soluble polymer contained in this anchor layer is
Since there is no compatibility with the wax contained in the hot-melt coloring material layer, which will be described in detail next, cohesive failure does not occur in the hot-melting coloring material layer, and therefore, high peelability is achieved by improving releasability. No deterioration in print quality.

Examples of the water-soluble polymer include polyvinyl alcohol, polyvinylpyrrolidone, gelatin, carboxymethylcellulose, methylcellulose, polyethylene oxide, gum arabic, water-soluble polyester, water-soluble polyurethane, water-soluble polyacrylic, and water-soluble polyamide.

Among these, those with a softening point of 100°C or higher are preferable, those with a softening point of 150°C or higher are particularly preferable, and those with a softening point of less than 100°C cause thermal melting to be formed on the anchor layer. In some cases, it may become impossible to stably apply the coloring material layer using the hot melt coating method.

Further, when the forming material of the support is polyethylene terephthalate, water-soluble polyurethane, water-soluble polyester and water-soluble polyacrylic are preferable because these have good adhesiveness to polyethylene terephthalate.

The content of the water-soluble polymer in the anchor layer is usually 5% by weight or more, preferably 20% by weight or more. If this content is less than 5% by weight, the peelability of the heat-melting coloring material layer may not be improved sufficiently.

In this invention, it is preferable that the anchor layer contains a filler together with the water-soluble polymer.

For example, as shown in Figure 2 (a) and (b),
By adding the filler 4 to the anchor layer 2 and making the anchor layer 2 and the heat-melting coloring material layer 3 adjacent to each other, the filler 4 is added to the interface between the heat-melting coloring material layer 3 and the anchor layer 2. Fine unevenness 5 can be formed according to the particle size. In addition, in FIG. 2(b), 10 is a transfer medium.

The unevenness has the effect of removing the gloss on the surface of the heat-melting coloring material layer transferred to the transfer medium, that is, the surface of the printed image, and improving the difficulty in reading the printed image caused by the gloss.

Examples of the filler include silica, talc, calcium carbonate, carbon black, alumina, acid clay, clay, magnesium carbonate, tin oxide, titanium white,
Graphite, curable resin particles, silicone resin particles, fluororesin particles, melamine resin particles, urea resin particles, benzoguanamine resin particles, acrylic resin particles, styrene resin particles, boron nitride, copper, iron, aluminum, iron oxide, tin oxide, Examples include aluminum oxide, magnesium oxide, and titanium nitride.

Among these, carbon black is preferred when the heat-fusible coloring material layer is black. This is because by adding carbon black to make the anchor layer black, the secrecy of the thermal transfer recording medium of the present invention can be improved. That is, after the heat-melting coloring material layer is peeled off from the interface with the anchor layer, a so-called white area corresponding to the peeled portion of the heat-melting coloring material layer is generated in the anchor layer remaining on the support. This is because it is possible to prevent blank areas from becoming obvious from the copy that they are transfer recorded contents.

However, when the heat-melting coloring material layer is black, the above effect is not limited to the above-mentioned carbon black; for example, the above-mentioned black pigment that does not have the function of a filler can be used. It can also be used. Furthermore, when the heat-melting coloring material layer is of a color other than black, a pigment having a color similar to that of the heat-melting coloring material layer may be used.

The average particle size of the filler is usually 0.2 pm or more.
It is within the range of m or less.

In addition to the water-soluble polymer and filler, the anchor layer may contain other components such as wax and surfactant.

The waxes include, for example, vegetable waxes such as carnauba wax, wood wax, auriculie wax, and Nispar wax; animal waxes such as beeswax, insect wax, shellac wax, and spermaceti wax; paraffin wax, icrocrystalline wax, polyethylene wax, ester wax, and Examples include petroleum waxes such as acid wax; mineral waxes such as montan wax, osikerite, and ceresin.

The wax has the function of adjusting the adhesive force between the anchor layer and the heat-melting coloring material layer, which will be described in detail below.

When using the wax, the content of the wax in the anchor layer is usually 95% by weight or less, preferably 80% by weight or less. This content is 95% by weight
If it exceeds 20%, the content of the water-soluble polymer in the anchor layer becomes relatively small, and the releasability of the heat-melting coloring material layer may not be sufficiently improved.

The surfactant has the function of adjusting the releasability of the heat-melting coloring material layer.

As the surfactant, various surfactants conventionally used in thermal transfer recording media, such as polyoxyethylene chain-containing compounds, can be used.

When using the surfactant, the content of the surfactant in the anchor layer is usually 30% by weight or less.

In this invention, the anchor layer containing the above components is formed on the support by an aqueous coating method.

The thickness of the anchor layer is usually within the range of 0.05 to 3 pm, preferably within the range of 0.1 to 1.5 pm. This layer thickness is less than 0.057 zm.

There is virtually no point in providing the anchor layer, and the object of the present invention, which is to improve the quality of the printed image by improving the releasability of the heat-melting coloring material layer, may not be achieved. On the other hand, even if it exceeds 3 ILm, no effect commensurate with the increase in layer thickness will be achieved.

On this anchor layer, a heat-melting coloring material layer, which will be described next, is usually laminated adjacent thereto.

- Heat-melting coloring material layer - The heat-melting coloring material layer usually contains a coloring material, a heat-melting substance, and a thermoplastic resin.

The layer thickness of this heat-melting coloring material layer is usually 0.5 to 8 #Lm.
within the range of 1.0 to 6. It is within the range of Ou, m.

Examples of the coloring material include pigments such as inorganic pigments and organic pigments, and dyes.

Examples of the inorganic pigments include titanium dioxide, carbon black, zinc oxide, Prussian blue, cadmium sulfide, iron oxide, and chromates of lead, zinc, barium, and calcium.

Examples of the organic pigments include azo, thioindigo, anthraquinone, anthanthrone, and triphenedioxazine pigments, vat dye pigments, phthalocyanine pigments, such as copper phthalocyanine and its derivatives, and quinacridone pigments.

Examples of the organic dye include acid dyes, direct dyes, disperse dyes, oil-soluble dyes, and metal-containing oil-soluble dyes.

The content of the coloring material in the heat-melting coloring material layer is as follows.

Usually within the range of 5 to 35% by weight, preferably 1
It is within the range of 0 to 25% by weight.

Specific examples of the heat-melting substances include vegetable waxes such as carnauba wax, wood wax, auriculie wax, and Nispar wax; animal waxes such as beeswax, insect wax, shellac wax, and spermaceti wax; paraffin wax, microcrystalline wax, and polyethylene wax. , petroleum waxes such as ester waxes and acid waxes; and waxes such as mineral waxes such as montan wax, osichelite and ceresin; in addition to these waxes, palmitic acid, stearic acid, margaric acid, etc. and higher fatty acids such as behenic acid: higher alcohols such as palmityl alcohol, stearyl alcohol, behenyl alcohol, marganyl alcohol, myricyl alcohol, and eicosanol: higher fatty acids such as cetyl palmitate, myricyl palmitate, cetyl stearate, and myricyl stearate Esters; amides such as acetamide, propionic acid amide, palmitic acid amide, stearic acid amide and amide wax; and higher amines such as stearylamine, behenylamine and palmitylamine.

These may be used alone or in combination of two or more.

Among these, preferred is a wax whose melting point is within the range of 50 to 100°C as measured using Yanagimoto MJP-2.

The thermoplastic resins include ethylene copolymers, polyamide resins, polyester resins, polyurethane resins, polyolefin resins, acrylic resins, vinyl chloride resins, cellulose resins, rosin resins, ionomer resins, and petroleum resins. Resins such as natural rubber, styrene-butadiene rubber, isoprene rubber, and chloroprene rubber; Rosin derivatives such as ester gum, rosin maleic acid resin, rosin phenolic resin, and hydrogenated rosin; and phenolic resins; Examples include polymeric compounds having a softening point of 50 to 150°C, such as terpene resins, cyclopentadiene resins, and aromatic hydrocarbon resins.

These may be used alone or in combination of two or more.

In addition to the above-mentioned components, the heat-melting coloring material layer may contain a surfactant such as a polyoxyethylene chain-containing compound in order to adjust releasability.

The content of the heat-fusible substance in the heat-fusible coloring material layer is:
It is usually 50% by weight or more, preferably in the range of 50 to 97% by weight, more preferably 60% by weight, based on the total weight of the thermofusible substance and the thermoplastic resin contained in this layer.
~95% by weight.

If the content of the heat-fusible substance to the total weight of the heat-fusible substance and the thermoplastic resin is less than 50% by weight, releasability may deteriorate.

Furthermore, inorganic or organic fine particles (metal powder, silica gel, etc.) or oils (linseed oil, mineral oil, etc.) can also be added.

The heat-melting coloring material layer can be formed by hot-melt coating method, water-based coating method,
Coating can be performed by a coating method using an organic solvent, but in this invention, a hot melt coating method is usually used for coating.6 - Others - In the thermal transfer recording medium of this invention may have a heat-softening layer between the anchor layer and the heat-melting coloring material layer.

The thermosoftening layer is usually a layer made of the above-mentioned thermoplastic resin and a thermofusible substance, and the film thickness is usually 0.6 to 0.6.
Within the range of 8.0 pm, preferably 1.0 to 6.0
It is in the range of end m.

The thermosoftening layer is preferably applied by a method of preparing an aqueous emulsion containing a thermofusible substance and a thermoplastic resin, and performing aqueous coating using this aqueous emulsion.

The aqueous emulsion can be applied by employing known methods such as a coating method using a wire bar, a gravure coating method, a kiss coating method, and a calendar coating method.

When water is removed from the applied aqueous emulsion, the particles constituting the emulsion (thermally softenable layer forming component particles) remain as they are or in a similar form (
For example, the heat-softening layer is composed of crushed spherical particles, and each particle is adhered to each other at a point or surface where it contacts an adjacent particle. Therefore, during thermal transfer, these spherical or similar particles act independently to some extent to provide good print quality.

Moreover, an overcoat layer can also be laminated on the heat-melting coloring material layer.

After each layer is coated in this manner, it is optionally subjected to a drying process, a surface smoothing process, etc., and then cut into a desired shape to obtain the thermal transfer recording medium of the present invention.

The thermal transfer recording medium thus obtained can be used in the form of a wide tape or typewriter ribbon generally used in line printers, etc., but the planar shape of the thermal transfer recording medium of the present invention is A sheet having the same width as the recording paper used in line printers is preferable.

The heat-sensitive transfer method using this heat-sensitive transfer recording medium is not different from a normal heat-sensitive transfer recording method, but will be explained using an example in which the most typical thermal head is used as a heat source.

First, the heat-melting coloring material layer of the heat-sensitive transfer recording medium and the medium to be transferred, such as transfer paper, are brought into close contact with each other, and if necessary, a heat pulse is further applied from the back side of the transfer paper using a platen.
A heat pulse is applied by a thermal head to locally heat the heat-melting coloring material layer corresponding to a desired printing or transfer pattern.

The temperature of the heated portion of the heat-melting coloring material layer increases, and the heat-melting coloring material layer is quickly softened and transferred onto the transfer medium.

[Example] Next, Examples and Comparative Examples of the present invention will be shown to further specifically explain the present invention. Note that "parts" used below indicate "parts by weight."

(Example 1) On a polyethylene terephthalate film with a thickness of 4.5 pm, the following anchor layer composition was applied in water to a film thickness of 0.5 ILm over a length corresponding to the width of JIS standard A4 paper. , an anchor layer in the thermal transfer recording medium of the present invention was formed.

Anchor polyvinyl alcohol 70 parts [manufactured by Kuraray: 'PVA 4034] Water-soluble polyester
...30 parts [manufactured by Toyobo ■: "Pyronal Kyo D-1200041" Next, the following hot-melt coloring material layer composition was mixed with a wire bar to a film thickness of 4.27 parts m. A hot-melt coloring material layer was formed on the anchor layer by hot-melt coating to produce a heat-sensitive transfer recording medium of the present invention.

Paraffin wax...40 parts Ester wax...20 parts Carbon black...25 parts Ethylene-vinyl acetate copolymer... ... 14 copies of the obtained thermal transfer recording medium were printed on a thermal printer (260 mm line height, 1800 pages).
I, platen rubber hardness 40 degrees) was used to record (print) on plain paper (Beck smoothness 50 seconds), and the print quality, glossiness, and confidentiality of the printed images were evaluated.

The results are shown in Table 1.

In addition, printing quality, glossiness, and confidentiality were each evaluated as follows.

Print quality: Voids and sharpness were visually observed.

Glossiness: Using a glossmeter, the glossiness of the printed image was measured under the condition that both the incident angle and the reflection angle were 60''.

Confidentiality: Visual observation was performed using reflected light for blanks after printing.

(Example 2) In Example 1, water-soluble polyurethane [manufactured by Dainippon Ink ■: "Hytran AP-40"] was used instead of the anchor layer composition in Example 1, and the layer thickness of the anchor layer was The test was carried out in the same manner as in Example 1 except that 0.5 JLm was changed to 0.71 Lm.

The results are shown in Table 1.

(Example 3) In Example 1, the following composition was used in place of the anchor layer composition in Example 1, and the thickness of the anchor layer was increased from 0.5 p-m to 1.5 JLm. The same procedure as in Example 1 was carried out except for the following changes.

The results are shown in Table 1.

Anchor water-soluble polyester 70 parts [manufactured by Toyobo ■: "Pyronal MD-1200J] Titanium oxide (average particle size t, sJLm) 30 parts (Example 4) Example 1 In place of the anchor layer composition in Example 1, the following composition was used, and the thickness of the anchor layer was changed from 0.5 JL111 to 1, Op, m
The procedure was carried out in the same manner as in Example 1 above, except that .

The results are shown in Table 1.

Anchor gelatin [manufactured by Takarazuka Gelatin ■] 20 parts Aqueous polyurethane emulsion 40 parts [manufactured by Kusunoki Kaoru ■]
r Neolets R-9314J] Colloidal boron nitride 40 parts (average particle size 0.4-1.0 p
Lm) (Example 5) In Example 1, the following composition was used in place of the anchor layer composition in Example 1, and the thickness of the anchor layer was changed from 0.5 JLm to 1.8 p, m. The procedure was carried out in the same manner as in Example 1 above, except that .

The results are shown in Table 1.

"Ototsusha" ■11 Polyvinyl alcohol...20 parts [manufactured by Kuraray ■: rPVA 403. ]Water-soluble polyester・
......20 parts [manufactured by Toyobo ■: "Pyronal MD-1200041 water-soluble polyamide...
...10 parts cured silicone resin powder...
30 parts [average particle size 1.5-2.0 #Lm; manufactured by Toshiba Silicone ■] Carbon black aqueous dispersion...20 parts (Comparative Example 1) In Example 1, the anchor layer was formed. A thermal transfer recording medium was produced in the same manner as in Example 1, except that the printing quality, glossiness, and confidentiality of the printed image were evaluated for the obtained thermal transfer recording medium.

The results are shown in Table 1.

(Comparative Example 2) In Example 1, instead of the water-based coating of the anchor layer composition in Example 1, polyester [manufactured by Nippon Polyurethane ■; r2:101. ] was applied using methyl ethyl ketone as a solvent, but a thermal transfer recording medium was manufactured in the same manner as in Example 1, and the print quality, glossiness, and confidentiality of the printed image of the obtained thermal transfer recording medium were evaluated. was evaluated.

The results are shown in Table 1.

(Comparative Example 3) In Example 1, in place of the aqueous coating of the anchor layer composition in Example 1, polyurethane [Toyobo ■
A heat-sensitive transfer recording medium was produced in the same manner as in Example 1, except that "Vylon 200J" was coated using methyl ethyl ketone as a solvent. The security and confidentiality were evaluated.The results are shown in Table 1.

Table 1 The symbols for each evaluation item have the following meanings.

Print quality: ◎: Both voids and sharpness are good.

O: Few voids, but sharpness It lacks quality.

×: Both void and sharpness are significant. Inferior.

Glossiness: O: Glossiness less than 20.

X: Glossiness 20 or more.

Confidentiality: ◎: The portion of the anchor layer corresponding to the printed image is unreadable.

○: Printed image on anchor layer Corresponding parts are legible.

(Evaluation) As is clear from Table 1, the thermal transfer recording medium of the present invention has excellent print quality of printed images compared to the thermal transfer recording media of Comparative Examples 1 to 3. When the anchor layer contains a filler as in Example 5, the gloss of the printed image is low, and when the anchor layer contains carbon black to make the anchor layer black as in Example 5, the gloss of the printed image is low. It was also confirmed that the retention property was excellent.

[Effects of the Invention] According to the present invention, (1) An anchor layer is provided between the support and the heat-melting coloring material layer, and this anchor layer realizes interfacial peeling with the heat-melting coloring material layer. Since it contains a water-soluble polymer that is not compatible with the wax in the hot-melt coloring material layer and does not cause cohesive failure in the hot-melting coloring material layer, it has excellent releasability of the hot-melting coloring material layer. (2) Therefore, the print quality of the printed image is high, and (3) if the anchor layer contains a filler, fine particles are added to the surface of the heat-melting coloring material layer to be transferred to the transfer medium. By forming unevenness and removing gloss on the surface of the printed image, it is possible to obtain an easily legible printed image. (4) Furthermore, since the anchor layer can be applied by water-based coating, It is possible to provide a thermal transfer recording medium having various advantages such as high safety and ease of manufacture.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view showing an example of the thermal transfer recording medium of the present invention, FIG. 2 (A) is an explanatory cross-sectional view showing another example, and FIG. FIG. 2 is an explanatory cross-sectional view showing a cross section of a printed image obtained by the thermal transfer recording medium of FIG. l...Support, 2...Anchor layer. 3...Thermofusible coloring material layer. Patent applicant: Konica Co., Ltd. Representative: Patent attorney: Naoki Fukumura. :,)'1'i~- Figure 1 Figure 2

Claims (2)

[Claims] (1) A heat-sensitive transfer recording medium characterized in that an anchor layer containing a water-soluble polymer is provided between a support and a heat-melting coloring material layer. (2) The thermal transfer recording medium according to claim 1, wherein the anchor layer further contains a filler.